KR102152514B1 - LBT for uplink transmission - Google Patents

Abstract

A method of controlling a user equipment (UE) includes determining an operating environment of the UE, selectively instructing to perform a first or second LBT or to use a first or second LBT parameter set.

Description

LBT for uplink transmission

This application claims priority to U.S. Provisional Application No. 62/292,002, filed on February 5, 2016, the disclosure of which is incorporated herein by reference.

The subject matter of the disclosed invention relates generally to telecommunications. Certain embodiments of the disclosed subject matter relate in particular to License Assisted Access (LAA), Listen Before Talk (LBT) and multicarrier LAA.

The Third Generation Partnership Project (3GPP) initiative, “License Assisted Access (LAA),” is intended to enable Long Term Evolution (LTE) equipment to operate in the unlicensed 5GHz radio spectrum. In this context, the unlicensed 5 GHz spectrum is used as a complement to the licensed radio spectrum. Thus, the device connects to the licensed spectrum (primary cell or PCell) and uses carrier aggregation to benefit from the additional transmission capacity of the unlicensed spectrum (secondary cell or SCell). In order to reduce the changes required to aggregate the licensed and unlicensed spectrum, LTE frame timing in the primary cell is used simultaneously in the secondary cell.

Regulations may prohibit transmission in unlicensed spectrum without prior channel sensing. Since the unlicensed spectrum has to be shared with other wireless devices of similar or different wireless technology, a so-called listen-before-talk (LBT) method is generally applied. Today, the unlicensed 5GHz spectrum is primarily used by equipment implementing the IEEE 802.11 wireless local area network (WLAN) standard. This standard is known as the marketing brand "Wi-Fi".

Both Wi-Fi and LAA can operate in multicarrier mode by transmitting simultaneously between multiple unlicensed channels in the 5GHz band. Wi-Fi follows a hierarchical multicarrier LBT scheme known as channel bonding.

LTE uses OFDM in the downlink and DFT spread OFDM (also referred to as single carrier FDMA) in the uplink. Accordingly, the basic LTE downlink physical resource may be viewed as a time-frequency grid as shown in FIG. 1, where each resource element corresponds to one OFDM subcarrier during one OFDM symbol interval. The uplink subframe has the same subcarrier spacing as the downlink and the number of SC-FDMA symbols in the same time domain as the OFDM symbols in the downlink.

In the time domain, the LTE downlink transmission is organized into radio frames of 10 ms, and as shown in Fig. 2, each radio frame consists of 10 equally sized subframes of length Tsubframe = 1 ms. In the case of a typical cyclic prefix, one subframe consists of 14 OFDM symbols. The period of each symbol is approximately 71.4 μs.

In addition, resource allocation in LTE is generally described in terms of a resource block, where a resource block corresponds to one slot (0.5 ms) in the time domain and 12 consecutive subcarriers in the frequency domain. A pair of two adjacent resource blocks in the time direction (1.0 ms) is known as a resource block pair. Resource blocks are numbered in the frequency domain starting with zero from one end of the system bandwidth.

The downlink transmission is dynamically scheduled, that is, in the current downlink subframe, in each subframe the base station transmits control information, which relates to which terminal data is transmitted to/on which resource block. Such control signaling is generally transmitted in the first 1, 2, 3, or 4 OFDM symbols in each subframe, and the number n = 1, 2, 3 or 4 is known as a CFI (Control Format Indicator). The downlink subframe also contains a common reference symbol, which is known to the receiver and is used, for example, for coherent demodulation of control information. A downlink system with an OFDM symbol of CFI=3 is shown in FIG.

Since LTE Rel-11, the resource allocation can also be scheduled on the enhanced physical downlink control channel (EPDCCH). A physical downlink control channel (PDCCH) is available only for Rel-8 to Rel-10.

The reference symbol shown in FIG. 1 is a cell specific reference symbol (CRS) and is used to support a number of functions including channel estimation and fine time and frequency synchronization for a specific transmission mode.

The PDCCH/EPDCCH is used to convey downlink control information (DCI) such as scheduling decisions and power control commands. More specifically, DCI includes:

-Downlink scheduling allocation, including PDSCH resource indication, transport format, hybrid ARQ information, and spatial multiplexing related control information (if applicable). The downlink scheduling assignment also includes a command for power control of the PUCCH used for transmission of the hybrid ARQ ACK in response to the downlink scheduling assignment.

-Uplink scheduling grant including PUSCH resource indication, transport format, and hybrid ARQ related information. The uplink scheduling grant also includes a command for power control of the PUSCH.

-Power control command for the terminal set as a complement to the command included in the scheduling assignment/grant.

One PDCCH/EPDCCH carries one DCI message including one of the information groups listed above. Since multiple terminals can be scheduled at the same time, and each terminal can be scheduled at the same time in both the downlink and uplink, there must be a possibility to transmit multiple scheduling messages within each subframe. Each scheduling message is transmitted on a separate PDCCH/EPDCCH resource, and as a result, there are generally multiple simultaneous PDCCH/EPDCCH transmissions in each subframe of each cell. In addition, in order to support different radio channel conditions, link adaptation in which the code rate of the PDCCH/EPDCCH is selected by adapting resource usage for the PDCCH/EPDCCH to match the radio channel conditions may be used.

The LTE Rel-10 standard supports a bandwidth of 20 MHz or higher. One important prerequisite of LTE Rel-10 is to ensure backward compatibility with LTE Rel-8. This also includes spectral compatibility. This means that LTE Rel-10 carriers wider than 20MHz must appear as multiple LTE carriers in LTE Rel-8 terminals. Each of these carriers may be referred to as a component carrier (CC). In particular, in the initial deployment of LTE Rel-10, the number of LTE Rel-10 capable terminals is expected to be smaller than that of many LTE legacy terminals. Accordingly, it is necessary to ensure efficient use of wide carriers even for legacy terminals, that is, it is possible for the legacy terminal to implement a carrier that can be scheduled in all parts of the broadband LTE Rel-10 carrier. One way to get this is through carrier aggregation (CA). CA means that the LTE Rel-10 terminal can receive a plurality of CCs having the same structure as or at least likely to have the Rel-8 carrier. CA is shown in FIG. 4. The CA-capable UE is assigned a primary cell (PCell) that is always activated and one or more secondary cells (SCell) that can be dynamically activated or deactivated.

The bandwidth of individual CCs as well as the number of aggregated CCs may differ depending on the uplink and downlink. A symmetric configuration refers to a case where the number of CCs is the same in a downlink and an uplink, whereas an asymmetric configuration refers to a case where the number of CCs is different. It should be noted that the number of CCs configured in one cell may be different from the number of CCs from the point of view of the terminal: For example, even if the cell is configured with the same number of uplink and downlink CCs, the terminal is Can support many downlink CCs.

A common feature of carrier aggregation is the ability to perform cross-carrier scheduling. In cross-carrier scheduling, the PDSCH is received in a CC other than the CC in which the PDCCH/EPDCCH is received. Similarly, the PUSCH will be transmitted on an associated CC other than the CC on which the uplink grant is received. This mechanism allows (E)PDCCH of one CC to schedule data transmission to another CC using a 3-bit CIF (Carrier Indicator Field) inserted at the beginning of the (E)PDCCH message. For data transmission to a given CC, the UE expects to receive the scheduling message of (E)PDCCH in only one CC, whether it is the same CC or another CC through cross-carrier scheduling; In addition, this mapping from (E)PDCCH to PDSCH is semi-statically configured.

In a typical WLAN deployment, Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is used for medium access. This means that transmission is started only when a channel is detected to perform a clear channel assessment (CCA) and the channel is declared as idle. When a channel is declared as busy, the channel is basically delayed until it is considered idle. When the ranges of multiple access points (APs) using the same frequency overlap, this means that all transmissions related to one AP may be delayed if transmissions to/from other APs within the range that can be detected at the same frequency. it means. In fact, this means that if multiple APs are in range, they will have to share the channel in time, and the throughput for individual APs can be severely degraded. An overall diagram of a Listen Before Talk (LBT) mechanism on a single unlicensed channel is shown in FIG. 5.

First, consider a single channel LBT case. After Wi-Fi station "A" transmits a data frame to station "B", station B must send an ACK frame back to station A with a delay of 16 μs. This ACK frame is transmitted by station B without performing LBT operation. In order to prevent other stations from interfering with this ACK frame transmission, the station must delay for a duration of 34 μs (referred to as DIFS) after the channel is observed to be occupied before reevaluating whether the channel is occupied.

Therefore, the first station to transmit performs CCA by detecting the medium for a fixed duration DIFS. If the medium is in the idle state, it is assumed that the station can take ownership of the medium and start the frame exchange sequence. If the medium is busy, the station waits for the medium to become idle, delays by DIFS, and waits for the next random backoff period.

In order for the station to continue to occupy the channel and further prevent other stations from accessing the channel, the station wishing to transmit again after the transmission is complete is required to perform random backoff.

In the case of multicarrier operation, Wi-Fi determines the transmission bandwidth of a frame, which may be, for example, 20 MHz, 40 MHz, 80 MHz, or 160 MHz according to a hierarchical channel combining method. In the 5GHz band, a wider Wi-Fi channel width of 40MHz, 80MHz, 160MHz or 80+80MHz is formed by combining 20MHz subchannels in a non-overlapping manner. If necessary, the predetermined primary channel performs a CW-based random access procedure after a delayed period, and then counts down the generated random number. The secondary channel only performs a quick CCA check for the PIFS duration (typically 25 μs) before the potential start of transmission to determine if an additional secondary channel is available for transmission. Based on the secondary CCA check result, the transmission is performed in a larger bandwidth, otherwise the transmission retreats to a smaller bandwidth. The Wi-Fi primary channel is always included in all transmissions, that is, transmission only on the secondary channel is not allowed.

For devices not using the Wi-Fi protocol, European Regulation EN 301.893, v.1.7.1 specifies the following requirements and minimum behavior for load-based clear channel evaluation. An example of EN 301.893 is shown in FIG. 6.

1) Before transmission or burst of transmission on the Operating Channel , the equipment must perform a Clear Channel Assessment (CCA) using "energy detect". The instrument should observe the working channel for the duration of the CCA observation time, which should not be less than 20 μs. The time of observation of the CCA using the equipment should be declared by the manufacturer. An operating channel is considered occupied if the energy level in the channel exceeds the threshold corresponding to the power level given in item 5 below. Once the device confirms that the channel is clear, it can transmit immediately (see item 3 below).

2) If the equipment confirms that the operating channel is occupied, it should not transmit to that channel. The equipment shall perform an extended CCA ( Extended CCA) inspection in which the working channel is observed for a time period of the CCA observation time multiplied by the duration of random element N. N defines the number of distinct idle slots causing the total Idle Period that must be observed before the start of the transmission. The value of N should be randomly selected within the range of 1...q each time an extended CCA is requested, and the value should be the value stored in the counter. The value of q is chosen by the manufacturer in the range 4...32. This selected value must be declared by the manufacturer (see clause 5.3.1q). The counter is decremented each time a CCA slot is considered "not occupied". When the counter reaches zero, the device will transmit.

Note 2: If the requirements of clause 4.9.2.3 are observed, the equipment may continue with Short Control Signaling Transmissions on this channel.

Note 3: For equipment that transmits simultaneously on multiple (adjacent or non-adjacent) operating channels, if the CCA check does not detect any signal on that channel, the equipment can continue to transmit on other operating channels.

3) The total time the equipment uses the operating channel is the Maximum Channel Occupancy Time , (13/32)×q ms should be less than, q is as defined in item 2 above, after which the device should perform the extended CCA as described in item 2 above.

4) When the intended packet is properly received by this device, the device can skip the CCA and immediately (see item 4) transmit management and control frames (eg ACK and block ACK frames). Without performing a new CCA, the continuous sequence of transmissions by the equipment shall not exceed the maximum channel occupancy time defined in item 3 above.

Note 4: For the purpose of multicast, it is allowed for the transmission of ACKs (related to the same data packet) of individual devices to occur in sequence.

5) The energy detection threshold for CCA should be proportional to the maximum transmit power (PH) of the transmitter: For an eirp (Equivalent Isotropically Radiated Power) transmitter of 23 dBm, the CCA threshold level (TL) is -73 dBm/ when input to the receiver. It must be below MHz (assuming a 0dBi receiving antenna). For other transmit power levels, the CCA threshold level TL should be calculated using the following formula: TL = -73dBm/MHz + 23-PH (assuming the 0dBi receive antenna and PH is specified in dBm e.i.r.p.).

So far, the spectrum used in LTE is dedicated to LTE. This has the advantage that the LTE system does not have to worry about coexistence with other non-3GPP radio access technologies in the same spectrum, and the spectrum efficiency can be maximized. However, the spectrum allocated to LTE is limited and cannot meet the increased demand for greater throughput from applications/services. Therefore, in addition to the licensed spectrum, a new research agenda for extending LTE in 3GPP to use the unlicensed spectrum has been launched.

Using Licensed-Assisted Access for unlicensed spectrum, the UE is connected to the PCell of the licensed band and one or more SCells of the unlicensed band, as shown in FIG. 7. In this description, the secondary cell of the unlicensed spectrum is denoted as an LAA secondary cell (LAA SCell). The LAA SCell can operate in DL-only mode, or it can operate with UL and DL traffic. In addition, future LTE nodes can operate in a standalone mode in a license-exempt channel without the support of a licensed cell. Naturally, the unlicensed spectrum can be used simultaneously by several different technologies. Therefore, as described above, LAA should consider coexistence with other systems such as IEEE 802.11 (Wi-Fi).

For unrestricted coexistence with the Wi-Fi system, transmission in the SCell must conform to the LBT protocol in order to avoid causing collisions and serious interference to ongoing transmission. This includes performing LBT before the start of transmission and limiting the maximum duration of a single transmission burst. The maximum transmission burst duration is specified according to national and regional regulations, for example, 4 ms in Japan and 13 ms in accordance with EN301.893. An example in the context of LAA is shown in FIG. 8, along with another example of the transmission burst duration in the LAA SCell where the maximum allowed transmission duration is limited to 4 ms. The eNB obtains channel access by performing LBT before transmitting data in the DL. The control channel is transmitted during the transmission duration of the eNB to schedule a specific UE to transmit on the UL at a specific time later. After the eNB releases the channel, the scheduled UEs perform LBT to determine whether they can transmit on the channel at a specific time.

8 shows a LAA for an unlicensed spectrum using LBT and LTE carrier aggregation to achieve a desired level of coexistence with other unlicensed band technologies.

Using LTE Carrier Aggregation (CA) introduced in Rel-10, it is possible to aggregate radio resources from multicarriers that may be in the same band or in different bands to improve the maximum transmission speed, system capacity and user experience. .

In Rel-13, Licensed-Assisted Access (LAA) aroused interest by expanding LTE carrier aggregation capabilities in the direction of capturing spectrum opportunities in unlicensed spectrum in the 5GHz band. WLANs currently operating in the 5GHz band already support 80MHz in the field, and 160MHz should follow the wave 2 deployment of IEEE 802.11ac. As a further enhancement of CA, it is necessary to enable multicarrier operation for unlicensed carriers using LAA. In LTE Rel-13, the extension of the CA framework of more than 5 carriers has begun. The goal is to support up to 32 carriers in both UL and DL.

In a specific embodiment of the disclosed subject matter, a method of controlling a user equipment (UE) includes determining an operating environment of the UE, and performing a first or second LBT procedure according to the determined operating environment, or to perform a first or second LBT. And selectively instructing the UE to use the parameter set.

In a specific related embodiment, instructing the UE includes transmitting information on an uplink scheduling control channel such as a PDCCH.

In certain related embodiments, the operating environment is determined based on statistics of uplink transmissions for the scheduled UE.

In certain related embodiments, the operating environment is determined based on an operating environment indicator provided from the UE based on the UE's own channel measurement. The operating environment indicator may indicate, for example, whether the UE observes a shorter interference burst that is more persistent than a long interference burst.

In certain related embodiments, determining the operating environment of the UE includes whether the UE is expected to experience a similar or different interference environment compared to at least one other UE to be scheduled in a different frequency subcarrier on the same cell as the UE. And determining. The method includes, for example, instructing the UE to perform a first LBT procedure or to use a first LBT parameter set, if it is determined that the UE is expected to experience a similar interference environment, and otherwise, the UE provides a different interference environment. If it is determined that it is expected to be experienced, it may further include instructing the UE to perform a second LBT procedure or to use a second LBT parameter set. Alternatively, the method may further comprise determining that if it is determined that the one or more scheduled UEs do not perform UL transmission at a predetermined time, then determining that the UE is expected to experience a different interference environment. As another alternative, the method includes maintaining a 1-bit value indicating whether the UE and at least one other UE have successfully completed the last scheduled UL transmission, and the UE has similar or different values based on the 1-bit value. It may further comprise determining whether it is expected to operate in an interfering environment. In another embodiment, the method includes the steps of maintaining a percentage value indicating a frequency at which any of the UE or at least one other UE successfully completes the previously scheduled UL transmission, and the UE is based on the percentage value. It may further comprise determining whether it is expected to operate in a similar or different interference environment.

In certain related embodiments, the second LBT procedure or the second LBT parameter set differs from the first LBT procedure or the first LBT parameter set in that an additional LBT opportunity is provided for the scheduled duration. The scheduled duration may include, for example, multiple subframes, the second LBT procedure or the second LBT parameter set provides at least one LBT opportunity in each subframe of the scheduled duration, and the first LBT The procedure or the first LBT parameter set does not provide at least one LBT opportunity in each subframe of the scheduled duration.

In some embodiments of the disclosed subject matter, a method of operating a user equipment (UE) comprises, depending on the determined operating environment, an instruction to perform a first or second LBT procedure or an instruction to use a first or second LBT parameter set. Receiving and, in accordance with the received instruction, performing a first or second LBT procedure or using a first or second LBT parameter set.

In certain related embodiments, the indication is transmitted on an uplink (UL) scheduling control channel.

In certain related embodiments, the operating environment is determined based on statistics of UL transmissions for scheduled UEs.

In certain related embodiments, the operating environment is determined based on an operating environment indicator provided from the UE to the radio access node based on the UE's own channel measurement. The operating environment indicator may indicate, for example, whether the UE observes a shorter interference burst that is more persistent than a long interference burst.

In certain related embodiments, the operating environment of the UE is determined according to whether the UE is expected to experience a similar or different interference environment compared to at least one other UE to be scheduled in a different frequency subcarrier on the same cell as the UE.

In certain related embodiments, the operating environment of the UE is determined according to whether the UE is expected to experience a similar or different interference environment compared to at least one other UE to be scheduled in a different frequency subcarrier on the same cell as the UE. In such an embodiment, when the UE is expected to experience a similar interference environment, indicate to perform the first LBT procedure or use the first LBT parameter set, otherwise when the UE is expected to experience a different interference environment, And receiving an instruction to perform a second LBT procedure or an instruction to use a second LBT parameter set.

In certain related embodiments, the second LBT procedure or the second LBT parameter set differs from the first LBT procedure or the first LBT parameter set in that an additional LBT opportunity is provided for the scheduled duration. The scheduled duration may include multiple subframes, and the second LBT procedure or the second LBT parameter set provides at least one LBT opportunity in each subframe of the scheduled duration, and the first LBT procedure or the first The LBT parameter set does not provide at least one LBT opportunity in each subframe of the scheduled duration.

In some embodiments of the disclosed subject matter, a radio access node configured to control a user equipment (UE) is configured to determine an operating environment of the UE and, depending on the operating environment, to perform a first or second LBT procedure or to perform a first or At least one memory, transceiver, and processor collectively configured to selectively instruct the UE to use the 2 LBT parameter set is included.

In certain related embodiments, instructing the UE includes transmitting information on the uplink scheduling control channel.

In certain related embodiments, the operating environment is determined based on statistics of uplink transmissions for the scheduled UE.

In certain related embodiments, the operating environment is determined based on an operating environment indicator provided from the UE based on the UE's own channel measurement.

In certain related embodiments, the operating environment indicator indicates whether the UE observes a shorter interference burst that is more persistent than a long interference burst.

In certain related embodiments, the operating environment of the UE comprises determining whether the UE is expected to experience a similar or different interference environment compared to at least one other UE to be scheduled in a different frequency subcarrier of the same cell as the UE. do. At least one memory, transceiver, processor, when determining that the UE is expected to experience a similar interference environment, to instruct the UE to perform the first LBT procedure or to use the first LBT parameter set, otherwise the UE may have a different interference environment When determining that it is expected to experience a second LBT procedure or to instruct the UE to use a second LBT parameter set, it may be further collectively configured. Alternatively, the at least one memory, transceiver, and processor are further collectively configured to determine that the UE is expected to experience a different interference environment when determining that the one or more scheduled UEs do not perform UL transmission at a predetermined time. As yet another alternative, the at least one memory, transceiver, and processor are configured to maintain a 1-bit value indicating whether the UE and at least one other UE successfully complete the last scheduled UL transmission, and the UE to the 1-bit value. It may be further collectively configured to determine whether it is expected to operate in a similar or different interfering environment based. As another alternative, the at least one memory, transceiver, and processor may maintain a percentage value indicating how often the UE or at least one other UE successfully completes previously scheduled UL transmission, and based on the percentage value, the UE Is further collectively configured to determine whether it is expected to operate in a similar or different interference environment.

In certain related embodiments, the second LBT procedure or the second LBT parameter set differs from the first LBT procedure or the first LBT parameter set in that an additional LBT opportunity is provided for the scheduled duration. The scheduled duration may include multiple subframes, and the second LBT procedure or the second LBT parameter set provides at least one LBT opportunity in each subframe of the scheduled duration, and the first LBT procedure or the first The LBT parameter set does not provide at least one LBT opportunity in each subframe of the scheduled duration.

In some embodiments of the disclosed subject matter, a user equipment (UE) includes a memory, a transceiver, and at least one processor collectively configured as follows:

Depending on the determined operating environment, to receive an instruction to perform a first or second LBT procedure or an instruction to use a first or second LBT parameter set, and to perform the first or second LBT procedure or to, according to the received instruction, It is collectively configured to use 1 or 2 LBT parameter sets.

In certain related embodiments, the indication is that information is transmitted on an uplink (UL) scheduling control channel.

In certain related embodiments, the operating environment is determined based on statistics of UL transmissions for scheduled UEs.

In certain related embodiments, the operating environment is determined based on the operating environment indicator provided to the radio access node from the UE based on the UE's own channel measurement. The operating environment indicator, for example, may indicate whether the UE is observing a short interference burst that is more persistent than a long interference burst.

The operating environment of the UE may be determined according to whether the UE is expected to experience a similar or different interference environment compared to at least one other UE to be scheduled in a different frequency subcarrier of the same cell as the UE. The method provides an indication to perform a first LBT procedure or an indication to use a first LBT parameter set when the UE is expected to experience a similar interference environment, otherwise, when the UE is expected to experience a different interference environment, the second It may further include receiving an instruction to perform an LBT procedure or an instruction to use a second LBT parameter set.

In certain related embodiments, the second LBT procedure or the second LBT parameter set differs from the first LBT procedure or the first LBT parameter set in that an additional LBT opportunity is provided for the scheduled duration. The scheduled duration includes multiple subframes, the second LBT procedure or the second LBT parameter set provides at least one LBT opportunity in each subframe of the scheduled duration, and the first LBT procedure or the first LBT parameter The set does not provide at least one LBT opportunity in each subframe of the scheduled duration.

In certain related embodiments, a method of operating a network node in a wireless communication system includes determining a load of the wireless communication system, determining an LBT procedure or LBT parameter for a plurality of user equipments (UEs) based on the determined load. , Instructing the UE device to perform the determined LBT procedure or to use the determined LBT parameter.

In a specific related embodiment, determining the LBT procedure or LBT parameter comprises scheduling the UE device based on the determined second, whether any scheduled UE device is scheduled in one subframe or one or more consecutive subframes simultaneously. Determining whether the scheduled UE device is simultaneously scheduled in one subframe or one or more consecutive subframes, determining an LBT procedure or an LBT parameter.

The drawings show selected embodiments of the disclosed subject matter. Like reference numerals in the drawings represent the same features.
1 shows an LTE downlink physical resource.
2 shows an LTE time domain structure.
3 shows a typical downlink subframe.
4 shows carrier aggregation.
5 shows the LBT in WiFi.
6 shows the LBT of EN 301.893.
7 shows a CA capable UE configured with one LAA SCell.
8 shows an LAA for an unlicensed spectrum using LTE carrier aggregation and LBT to ensure a desired level of coexistence with other unlicensed band technologies.
9 illustrates UL user multiplexing in a LAA SCell when a user experiences the same or similar interference environment according to an embodiment of the disclosed subject matter.
10 illustrates UL user multiplexing in a LAA SCell when a user experiences a different interference environment according to an embodiment of the disclosed subject matter.
11 illustrates UL user multiplexing in a LAA SCell when a user experiences a different interference environment according to an embodiment of the disclosed subject matter.
12 illustrates a communication system according to an embodiment of the disclosed subject matter.
13A illustrates a wireless communication device in accordance with an embodiment of the disclosed subject matter.
13B illustrates a wireless communication device in accordance with an embodiment of the disclosed subject matter.
14A illustrates a radio access node in accordance with an embodiment of the disclosed subject matter.
14B illustrates a radio access node according to another embodiment of the disclosed subject matter.
15 illustrates a radio access node according to another embodiment of the disclosed subject matter.

The following description shows various embodiments of the disclosed subject matter. These examples are provided as teaching examples and should not be construed as limiting the scope of the disclosed subject matter. For example, certain details of the disclosed embodiments may be modified, omitted, or expanded without departing from the scope of the disclosed subject matter.

In current LTE, multiple UEs can be scheduled to use different frequency subcarriers in the same cell. For example, two UEs can be scheduled by the eNB to each use half of the subcarriers. In such a situation, as shown by way of example in FIGS. 9 and 10, system performance depends to some extent on whether the UE experiences the same or different interference environment.

9 shows an example of UL user multiplexing in LAA SCell when a user experiences the same or similar interference environment. As shown in FIG. 9, if two UEs experience the same or similar interference environment in the unlicensed band, both will be able to finish LBT and start transmission as scheduled by the eNB.

10 shows an example of UL user multiplexing in LAA SCell when a user experiences a different interference environment. As shown in FIG. 10, if two users experience different interference environments, one of the UEs may end LBT and start transmission. Other UEs do not finish the LBT procedure within time so that transmission can start at a specific time, so transmission will be impossible. There are two drawbacks to this solution.

First, as shown in FIG. 10, a subcarrier scheduled for the second UE is not used. Even if the UE is allowed to transmit according to the LBT protocol, the UE will only use the subcarrier scheduled for it and cannot transmit on the unused subcarrier. This unused resource degrades system performance and user throughput.

Second, as further shown in FIG. 10, even if the interference stops soon, the subcarriers scheduled for the second UE remain unused for the duration scheduled for the UE. This is because the second UE will observe that the channel is occupied due to the ongoing transmission from the first UE.

This disadvantage can be observed even when the UE is scheduled for multiple LAA SCells. When the UE observes a different interference environment on the scheduled SCell, it can transmit only a subset of the scheduled SCell. Other SCells are not used for the scheduled duration for the UE.

Recognizing the above and other potential drawbacks of the conventional approach, in the following specific embodiment, the eNB adapts the scheduled UE's LBT procedure to the operating environment. The adapted LBT procedure is provided (ie, signaled) to the scheduled UE over the control channel. The UE is instructed to perform the first LBT procedure in the first operating environment or to use the first LBT parameter set. The UE is instructed to perform a second LBT procedure in a second operating environment or to use a second LBT parameter set. In general, the term “direct” may refer to any communication mechanism intended to cause a device to perform a specific action. For example, an instruction may take the form of an explicit command to perform a particular command, or may include the transmission of information (eg, an implicit instruction) that causes the device to operate in a particular manner. As an example of an implicit indication, the network node may signal the LAA UL LBT parameter to the UE through a PDCCH DCI message. For example, if the DCI message has a first format, the UE can perform the first LBT procedure based on the corresponding LAA UL LBT parameter, and if the DCI message has a second format, the UE is the corresponding LAA The second LBT procedure may be performed based on the UL LBT parameter.

In yet another specific embodiment below, the eNB determines an operating environment based on statistics of UL transmission for the scheduled UE.

In another specific embodiment below, the UE provides an operating environment indication to the eNB based on its own channel measurement.

The described embodiments can be variously applied to both LAA LTE and standalone LTE operation for both FDD and TDD systems. Certain embodiments can also be applied to systems operating in completely unlicensed spectrum, such as for example a Multifire system.

In some embodiments, the eNB instructs (eg, signals) the selected LBT procedure or LBT parameter set to the scheduled UE in the UL scheduling control channel. The UL scheduling control channel may be, for example, a PDCCH, and indication or signaling may include, for example, transmission of DCI. The eNB may instruct the scheduled UE to perform the first LBT procedure in the first operating environment or to use the first LBT parameter set. The first operating environment may correspond to a case where a scheduled UE is expected to experience a similar or the same interference environment. If the eNB observes that a certain scheduled UE does not perform UL transmission at a specified time, it may determine that the UE has experienced a different interference environment than other UEs that successfully complete UL transmission. When the eNB reschedules the UE (perhaps with another UE), the eNB instructs the scheduled UE to perform a second LBT procedure or use a second LBT parameter set.

The second LBT procedure or the second LBT parameter set is different from the first LBT procedure or the first LBT parameter set in that an additional LBT opportunity is provided for the scheduled duration. Such an opportunity may include, for example, a clear CCA as described in connection with FIG. 11.

11 shows an example of a second LBT procedure or a second LBT parameter set, that is, an example of UL user multiplexing in the LAA SCell when a user experiences a different interference environment. In this example, regardless of whether the UE has acquired channel access, it is instructed to perform the CCA check at the beginning of each subframe. With this feature, the second UE can discover an available channel during this CCA check opportunity when the interference is stopped. Accordingly, as shown in the figure, the second UE can start transmission, and the system can avoid leaving the scheduled resource not being properly used.

In a specific related embodiment, the eNB maintains UE-specific statistics on whether the UE successfully completes the scheduled UL transmission.

In one embodiment, the eNB maintains a 1-bit value for whether the UE successfully completes the last scheduled UL transmission. For a UE that has not completed the last scheduled UL transmission, the UE is expected to operate in a different interference environment.

In another embodiment, the eNB maintains a 1% value for how often the UE successfully completes previously scheduled UL transmission. For UEs with a high rate of not completing previously scheduled UL transmissions, the UEs are expected to operate in different interference environments.

The eNB determines an LBT procedure or LBT parameter set for the scheduled UE based on whether some or all of the scheduled UEs are expected to operate in different interference environments.

The UE often observes and measures the channel to see if there is a data or control channel transmitted from the eNB to the UE. Therefore, the UE has an opportunity to observe the intra-channel interference pattern. The UE may signal the type or characteristic of the operating environment to the eNB. This information may be provided to the eNB by the UE through a UL physical layer control channel or a higher layer control message in the UL data channel. One non-limiting example of such signaling is to indicate whether the UE observes a shorter interference burst that is persistent than a long interference burst.

In a specific embodiment, the eNB determines the LBT procedure or LBT parameter for the scheduled UE based on the load in the system. In a non-limiting example based on the load of the system, the eNB schedules the UE. Based on the scheduling information, the eNB may determine whether there is a UE scheduled simultaneously in a subframe or in one or more consecutive subframes. According to the distribution of the scheduled UE in the upcoming subframe, the eNB may determine the LBT procedure or LBT parameter set for the scheduled UE. One non-limiting example is that some groups of scheduled UEs use the LBT parameter set, such as performing a CCA check at the beginning of each subframe regardless of whether some groups of the scheduled UEs have acquired channel access. . With this feature, the second UE can discover an available channel during this CCA check opportunity when the interference is stopped. Another non-limiting example is that the LBT parameter includes a set of subframe indicators in which the UE should perform LBT. This means that if the UE accesses the channel before the indexed subframe, the UE must release the channel and retry LBT for that subframe. The set of subframes may be the same for all UEs, or may be different for groups or individual UEs.

In another variant of this embodiment, the eNB instructs the UE not to perform any LBT, but simply pause for a specific period, e.g. 25 or 16 microseconds, before resuming transmission in a subsequent scheduled subframe. can do. That is, one of the LBT instructions is to simply pause without an additional LBT. This allows a UE that starts transmitting in its subsequent subframe to gain access to the channel, whereas a UE that has already started transmitting in a previous subframe and has a valid UL grant for transmission in a subsequent subframe is very short. During the period, there is no need to change the UE's receiver hardware from Tx to Rx and back to Tx.

In another modified example of this embodiment, the eNB is before the scheduled subframe when transmission has not yet started, rather than continuing the random backoff procedure from the previous LBT procedure performed before the previous subframe that was not successfully accessed. For all LBT procedures attempted at, the random backoff procedure may be instructed to restart the UE. In this case, the eNB may provide a new random backoff counter to the UE in each scheduled subframe. The UE restarts the random backoff procedure before attempted transmission in all scheduled subframes. However, once transmission is successfully started in a scheduled subframe, no more random backoff procedure is performed before transmission in a subsequent scheduled subframe.

The described examples can be implemented in any suitable type of communication system that supports any suitable communication criteria and uses any suitable components. As an example, a specific embodiment may be implemented in a communication system as shown in FIG. 12. Although a specific embodiment has been described in connection with the LTE system and related terms, the disclosed concept is not limited to the LTE or 3GPP system. Also, although the term “cell” is mentioned, the described concept can also be applied in other contexts, such as beams used in 5G (5G) systems, for example.

Referring to FIG. 12, the communication system 1200 includes a plurality of wireless communication devices 1205 (e.g., UE, machine type communication (MTC) / machine-to-machine (M2M) UE) and a plurality of radio access nodes. (1210) (eg, eNodeB or other base station). The communication system 1200 is organized into cells 1215 that are connected to the core network 1220 through a corresponding radio access node 1210. The wireless access node 1210 is capable of communicating with the wireless communication device 1205 along with any additional elements suitable to support communication between the wireless communication device or between the wireless communication device and another communication device (eg, a landline telephone).

Although the wireless communication device 1205 may represent a communication device comprising any suitable combination of hardware and/or software, such a wireless communication device, in certain embodiments, may be as shown in more detail in FIGS. 13A and 13B. It can represent the same device. Similarly, although the illustrated radio access node may represent a network node comprising any suitable combination of hardware and/or software, such a node may, in certain embodiments, be shown in more detail in FIGS. 14A, 14B, 15. It can represent a device as.

13A, the wireless communication device 1300A includes a processor 1305 (e.g., CPUs (Central Processing Units), ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), and/or the like. ), a memory 1310, a transceiver 1315, and an antenna 1320. In certain embodiments, some or all of the functions described as being provided by the UE, MTC or M2M device and/or any other type of wireless communication device may execute instructions stored in a computer-readable medium such as memory 1310. It may be provided by the device processor. Alternative embodiments may include additional components other than those shown in FIG. 13A that may be responsible for providing certain aspects of the functionality of the device, including any functionality described herein.

Referring to FIG. 13B, the wireless communication device 1300B includes at least one module 1325 configured to perform one or more corresponding functions. Examples of such functionality include various method steps or combinations of method steps as described herein for a wireless communication device. In general, a module may include any suitable combination of software and/or hardware configured to perform a corresponding function. For example, in some embodiments, a module includes software configured to perform a corresponding function when performing an associated platform, as shown in FIG. 13A.

14A, the radio access node 1400A includes a node processor 1405 (e.g., CPUs (Central Processing Units), ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), and/or similar Ones), a memory 1410, and a control system 1420 including a network interface 1415. Further, the radio access node 1400A includes at least one radio unit 1425 including at least one transmitter 1435 and at least one receiver connected to at least one antenna 1430. In some embodiments, the wireless unit 1425 is external to the control system 1420 and is connected to the control system 1420, for example via a wired connection (eg, an optical cable). However, in some other embodiments, wireless unit 1425 and potentially antenna 1430 are integrated with control system 1420. The node processor 1405 operates to provide at least one function 1445 of the radio access node 1400A as described herein. In some embodiments, the functionality is implemented in software, for example, stored in memory 1410 and performed by node processor 1405.

In certain embodiments, some or all functions described as being provided by a base station, NodeB, eNB, and/or any other type of network node are stored in a computer-readable medium, such as memory 1410 shown in FIG. 14A. It may be provided from the node processor 1405 that performs the instruction. Alternative embodiments of the radio access node 1400 may include additional components to provide additional functionality, such as the functionality described herein and/or related support functionality.

14B, the radio access node 1400B includes at least one module 1450 configured to perform one or more corresponding functions. Examples of such functionality include various method steps or combinations of method steps as described herein for a radio access node. In general, a module may include any suitable combination of software and/or hardware configured to perform a corresponding function. For example, in some embodiments, a module includes software configured to perform a corresponding function when performing an associated platform, as shown in FIG. 14A.

15 is a block diagram illustrating a virtualized radio access node 1500 according to an embodiment of the disclosed subject matter. The concepts described with reference to FIG. 15 may be similarly applied to other types of network nodes. Also, other types of network nodes may have similar virtualized architectures. As used herein, the term “virtualized radio access node” refers to an implementation of a radio access node in which at least a portion of the functionality of the radio access node is implemented as a virtual component (e.g., physical Through a virtual machine running processing nodes).

Referring to FIG. 15, the radio access node 1500 includes a control system 1420 as described in connection with FIG. 14A.

The control system 1420 is connected to one or more processing nodes 1520 that are included or connected as part of the network 1525 through a network interface 1515. Each processing node 1520 includes one or more processors 405 (eg, CPUs, ASICs, FPGAs and/or the like), memory 1510, and network interface 1515.

In this example, the functionality 1445 of the radio access node 1400A described herein is implemented in one or more processing nodes 1520, or through the control system 1420 and one or more processing nodes 1520. Distributed in a way. In some embodiments, some or all functions of the radio access node 1400A described herein are implemented as virtual components implemented through one or more virtual machines in a virtual environment hosted by the processing node 1520. As will be appreciated by those of skill in the art, additional signaling or communication between processing node 1520 and control system 1420 is used to perform at least some of the desired functions 1445. As indicated by the dotted line, in some embodiments the control system 1420 may be omitted, in which case the wireless unit 1425 directly communicates with the processing node 1520 through appropriate network interference.

In some embodiments, the computer program includes an instruction, wherein when performed by at least one processor, the instruction is a radio access node (e.g., radio access node 1210 or 1400A) or described herein. The function of another node (processing node 1520) that implements one or more functions of the radio access node in the virtual environment according to any of the described embodiments is implemented.

16 and 17 are flowcharts illustrating examples of methods that may be performed in the various environments described above. Various operations in this way can be performed, for example, by various combinations of at least one memory, processor, and transceiver. They can also use various modules, software, etc., as described above.

According to FIG. 16, the method of controlling the UE is to perform the first or second LBT procedure or use the first or second LBT parameter set according to the step of determining the operating environment of the UE (S1605) and the determined operating environment. And selectively instructing the UE to be performed (S1610). Instructing the UE may include, for example, transmitting information on an uplink scheduling control channel.

The operating environment may be determined based on statistics of uplink transmissions for the scheduled UE. The operating environment may also be determined based on an operating environment indicator provided from the UE based on the UE's own channel measurement. The operating environment indicator may indicate, for example, whether the UE observes a shorter interference burst that is more persistent than a long interference burst.

Determining the operating environment of the UE comprises, for example, determining whether the UE is expected to experience a similar or different interference environment compared to at least one other UE to be scheduled in a different frequency subcarrier on the same cell as the UE. can do. In addition, the method comprises instructing the UE to perform a first LBT procedure or to use a first LBT parameter set when determining that the UE is expected to experience a similar interference environment, otherwise the method allows the UE to experience a different interference environment. When determining that it is expected to experience, it may further include instructing the UE to perform a second LBT procedure or to use a second LBT parameter set. Alternatively, the method may further include determining that the UE is expected to experience a different interference environment when determining that the one or more scheduled UEs do not perform UL transmission at a predetermined time. As yet another alternative, the method includes maintaining a 1-bit value indicating whether the UE and at least one other UE successfully complete the last scheduled UL transmission, and the UE has a similar or different interference environment based on the 1-bit value. It may further include determining that it is expected to work at. As another alternative, the method comprises the steps of maintaining a percentage value indicating the frequency at which the UE or at least one other UE successfully completes previously scheduled UL transmission, and the UE is in a similar or different interference environment based on the percentage value. It may further include determining whether it is expected to work on.

The second LBT procedure or the second LBT parameter set may be different from the first LBT procedure or the first LBT parameter set in that an LBT opportunity is provided for a scheduled duration. The scheduled duration may include, for example, multiple subframes, wherein the second LBT procedure or the second LBT parameter set provides at least one LBT opportunity in each subframe of the scheduled duration, and the first The LBT procedure or the first LBT parameter set does not provide at least one LBT opportunity in each subframe of the scheduled duration.

According to FIG. 17, the operating method of the UE includes receiving an instruction to perform a first or second LBT procedure or an instruction to use a first or second LBT parameter set according to the determined operating environment (S1705), and According to the instruction, performing the first or second LBT procedure or using the first or second LBT parameter set (S1710). The indication may be transmitted on the UL scheduling control channel, for example.

The operating environment can be determined, for example, based on statistics of UL transmissions for scheduled UEs. Alternatively, the operating environment may be determined based on the operating environment indicator provided by the UE to the radio access node based on the UE's own channel measurement. The operating environment indicator may indicate, for example, whether the UE observes a shorter interference burst that is more persistent than a long interference burst. As another alternative, the operating environment of the UE may be determined according to whether the UE is expected to experience a similar or different interference environment compared to at least one other UE to be scheduled in a different frequency subcarrier on the same cell as the UE.

The method includes instructing the UE to perform a first LBT procedure or use a first LBT parameter set when determining that the UE is expected to experience a similar interference environment, otherwise the UE is expected to experience a different interference environment. When determining, it may further include instructing the UE to perform the second LBT procedure or use the second LBT parameter set.

The second LBT procedure or the second LBT parameter set may be different from the first LBT procedure or the first LBT parameter set in that an additional LBT opportunity is provided for the scheduled duration. The scheduled duration may include, for example, multiple subframes, wherein the second LBT procedure or the second LBT parameter set provides at least one LBT opportunity in each subframe of the scheduled duration, and the first The LBT procedure or the first LBT parameter set does not provide at least one LBT opportunity in each subframe of the scheduled duration.

In the present specification, the following abbreviations may be used.

CCA Clear Channel Assessment

CW Contention Window

DCF Distributed Coordination Function

DIFS DCF Inter-frame Spacing

DL Downlink

DRS Discovery Reference Signal

eNB evolved NodeB, base station

LAA Licensed Assisted Access

LBT Listen Before Talk

MRBC Multiple Random Backoff Channels

PDCCH Physical Downlink Control Channel

PIFS PCF Inter-frame Spacing

PUSCH Physical Uplink Shared Channel

QCI QoS Class Identifier

QoS Quality of Service

SCell Secondary Cell

SIFS Short Inter-frame Spacing

SRBC Single Random Backoff Channel

TTI Transmission-Time Interval

UE User Equipment

UL Uplink

Although the subject matter of the disclosed invention has been presented above with reference to various embodiments, various changes in form and detail may be applied to the disclosed embodiments without departing from the entire scope of the disclosed subject matter.

Communication system 1200

Claims (44)

A method of controlling user equipment (UE) 1205, comprising:
Selectively instructing the UE 1205 to perform the first or second LBT procedure or use the first or second LBT parameter set,
The second LBT procedure or the second LBT parameter set is different from the first LBT procedure or the first LBT parameter set in that an additional LBT opportunity is provided during the scheduled duration, and the scheduled duration includes multiple subframes, and The 2 LBT procedure or the second LBT parameter set provides at least one LBT opportunity in each subframe of the scheduled duration, and the first LBT procedure or the first LBT parameter set is at least one in each subframe of the scheduled duration. The way, does not offer LBT opportunities. The method of claim 1,
Indicating the UE 1205 comprises transmitting information on an uplink scheduling control channel. The method of claim 1,
Further comprising determining an operating environment of the UE 1205 and performing a step of selectively instructing according to the determined operating environment,
The method of claim 1, wherein the operating environment is determined based on statistics of uplink transmissions for the scheduled UE. The method of claim 1,
Further comprising determining an operating environment of the UE 1205 and performing a step of selectively instructing according to the determined operating environment,
The method, wherein the operating environment is determined based on an operating environment indicator provided from the UE 1205 based on the UE's own channel measurement. The method of claim 4,
Further comprising determining an operating environment of the UE 1205 and performing a step of selectively instructing according to the determined operating environment,
The method of claim 1, wherein the operating environment indicator indicates whether the UE 1205 observes a shorter interference burst that is persistent than a longer interference burst. The method of claim 1,
Further comprising determining an operating environment of the UE 1205 and performing a step of selectively instructing according to the determined operating environment,
Determining the operating environment of the UE 1205 is that the UE will experience a similar or different interference environment compared to at least one other UE 1205 to be scheduled in a different frequency subcarrier on the same cell as the UE 1205. Determining whether it is expected or not. The method of claim 6,
When determining that the UE 1205 is expected to experience a similar interference environment, instructing the UE 1205 to perform the first LBT procedure or use the first LBT parameter set, otherwise the UE 1205 is different. When determining that it is expected to experience an interfering environment, instructing the UE 1205 to perform a second LBT procedure or use a second LBT parameter set. The method of claim 6,
The method further comprising determining that the UE 1205 is expected to experience a different interference environment when determining that the one or more scheduled UEs do not perform UL transmission at a predetermined time. The method of claim 6,
Maintaining a 1-bit value indicating whether the UE 1205 and at least one other UE successfully complete the last scheduled UL transmission, and the UE 1205 has a similar or different interference environment based on the 1-bit value. Determining that it is expected to work at. The method of claim 6,
Maintaining a percentage value indicating how often the UE 1205 or any at least one other UE successfully completes previously scheduled UL transmission, and the UE 1205 has similar or different interference based on the percentage value. Determining whether it is expected to operate in the environment. A method of operating user equipment (UE) 1205, comprising:
Receiving an instruction to perform a first or second LBT procedure or an instruction to use a first or second LBT parameter set; and
According to the received instruction, performing a first or second LBT procedure or using a first or second LBT parameter set,
The second LBT procedure or the second LBT parameter set is different from the first LBT procedure or the first LBT parameter set in that an additional LBT opportunity is provided during the scheduled duration, and the scheduled duration includes multiple subframes, and The 2 LBT procedure or the second LBT parameter set provides at least one LBT opportunity in each subframe of the scheduled duration, and the first LBT procedure or the first LBT parameter set is at least one in each subframe of the scheduled duration. The way, does not offer LBT opportunities. The method of claim 11,
The indication is sent on an uplink (UL) scheduling control channel. The method of claim 11,
The instruction to perform the first or second LBT procedure or the instruction to use the first or second LBT parameter set is determined according to the operating environment of the UE,
The operating environment is determined based on statistics of UL transmissions for the scheduled UE. The method of claim 11,
The instruction to perform the first or second LBT procedure or the instruction to use the first or second LBT parameter set is determined according to the operating environment of the UE,
The method, wherein the operating environment is determined based on an operating environment indicator provided by the UE 1205 to the radio access node 1210 based on the UE's own channel measurement. The method of claim 14,
The instruction to perform the first or second LBT procedure or the instruction to use the first or second LBT parameter set is determined according to the operating environment of the UE,
The method of claim 1, wherein the operating environment indicator indicates whether the UE 1205 observes a shorter interference burst that is persistent than a longer interference burst. The method of claim 11,
The instruction to perform the first or second LBT procedure or the instruction to use the first or second LBT parameter set is determined according to the operating environment of the UE,
The operating environment of the UE 1205 depends on whether the UE is expected to experience a similar or different interference environment compared to at least one other UE 1205 to be scheduled in a different frequency subcarrier on the same cell as the UE 1205. Determined according to the method. The method of claim 16,
When determining that the UE 1205 is expected to experience a similar interference environment, performing a first LBT procedure or receiving an indication to use the first LBT parameter set, otherwise the UE 1205 may experience a different interference environment. When determining that it is expected to be expected, receiving an indication to perform a second LBT procedure or use a second LBT parameter set. As a radio access node 1210 configured to control a user equipment (UE) 1205:
At least one memory, transceiver and processor:
It is collectively configured to instruct the UE 1205 to perform the first or second LBT procedure or to selectively use the first or second LBT parameter set,
The second LBT procedure or the second LBT parameter set is different from the first LBT procedure or the first LBT parameter set in that an additional LBT opportunity is provided during the scheduled duration, and the scheduled duration includes multiple subframes, and The 2 LBT procedure or the second LBT parameter set provides at least one LBT opportunity in each subframe of the scheduled duration, and the first LBT procedure or the first LBT parameter set is at least one in each subframe of the scheduled duration. Wireless access node, which does not provide an LBT opportunity. The method of claim 18,
A radio access node, wherein at least one memory, transceiver and processor are collectively configured to perform the method according to any one of claims 2 to 10. As User Equipment (UE) 1205:
Memory, transceiver, and at least one processor:
Receive an instruction to perform a first or second LBT procedure or use a first or second LBT parameter set;
According to the received instruction, collectively configured to perform a first or second LBT procedure or to use a first or second LBT parameter set,
The second LBT procedure or the second LBT parameter set is different from the first LBT procedure or the first LBT parameter set in that an additional LBT opportunity is provided during the scheduled duration, and the scheduled duration includes multiple subframes, and The 2 LBT procedure or the second LBT parameter set provides at least one LBT opportunity in each subframe of the scheduled duration, and the first LBT procedure or the first LBT parameter set is at least one in each subframe of the scheduled duration. User equipment, which does not provide an LBT opportunity. The method of claim 20,
User equipment, wherein a memory, a transceiver and at least one processor are collectively configured to perform the method according to any of claims 12 to 17. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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